Releasable locking mechanism for pushbutton switch with pilot-lamp assembly

ABSTRACT

A four-sided pushbutton 1 projecting from the top of a housing 4 is secured to a switch-actuating rod 3 traversing a lamp holder 7 which supports the sockets of four pilot lamps 8, this holder consisting of two superposed and fixedly interconnected plates 71, 72 rotatably bracketing a flange 91 of a guide sleeve 9 for the rod in axially fixed position with reference to the holder. Upon depression of the pushbutton, the lower end of the rod operates a switch structure b; a cross-pin 33 on the rod normally engages in a pair of diametrically opposite longitudinal slots 92 of the sleeve to entrain the latter rotatorily for detaching a pair of lugs 93 at the foot of the sleeve from respective shoulders 52 in a depending neck 5 of the housing whereby, upon sufficient withdrawal of the pushbutton from the housing to enable its rotation, the lamp holder, the sleeve and the pushbutton with its rod can be bodily extracted from the housing as the cross-pin rises to the top of the slots at the level of the flange 91 to bear from below upon the upper holder plate 71. Such rotation is prevented in a lower position of the pin 33 by a projection 72d depending from the lower holder plate 72; another projection 43, rising from the housing bottom, coacts with the depending projection 72d to insure correct reinsertion of the extracted unit into the housing. Proper relative orientation of the pushbutton and the pilot lamps is insured by an indexing spring 74 which normally fits into an elongate notch 31 on one side of the rod 3 to allow depression of the pushbutton 1 but which falls into another, lower notch 34 on the opposite side of the rod, blocking a descent thereof, if the pushbutton is rotated in the wrong sense to re-engage the lugs 93 of the sleeve with the shoulders 52.

lJnite States atent n 1 Ando [54] RELEASABLE LOCKING MECHANHSM F OR PUSHBUTTON SWITCH WITH PILQT-LAMP ASSEMBLY [75] Inventor: Sadao Ando,

Kanagawa-ken, Japan Fujisawa-shi Laete ..200/167 A Primary vExaminerRobert K. Schaefer Assistant Examiner-William J. Smith Attorney-Karl F. Ross 57 ABSTRACT A four-sided pushbutton 1 projecting from the top of a housing 4 is secured to a switch actuating rod 3 [451 ay l, 1973 rotatably bracketing a flange 91 of a guide sleeve 9 for the rod in axially fixed position with reference to the holder. Upon depression of the pushbutton, the lower end of the rod operates a switch structure b; a crosspin 33 on the rod normally engages in a pair of diametrically opposite longitudinal slots 92 of the sleeve to entrain the latter rotatorily for detaching a pair of lugs 93 at the foot of the sleeve from respective shoulders 52 in a depending neck 5 of the housing whereby, upon sufficient withdrawal of the pushbutton from the housing to enable its rotation, the lamp holder, the sleeve and the pushbutton with its rod can be bodily extracted from the housing as the cross-pin rises to the top of the slots at the level of the flange 91 to bear from below upon the upper holder plate 71. Such rotation is prevented in a lower position of the pin 33 by a projection 72d depending from the lower holder plate 72; another projection 43, rising from the housing bottom, coacts with the depending projection 72d to insure correct reinsertion of the extracted unit into the housing. Proper relative orientation of the pushbutton and the pilot lamps is insured by an index ing spring 74 which normally fits into an elongate notch 31 on one side of the rod 3 to allow depression of the pushbutton 1 but which falls into another, lower notch 34 on the opposite side of the rod, blocking a 8 Claims, 19 Drawing Figures Pate nte d May 1, 1973 6 Sheets-Sheet 1 Sadao ANDO INVENTOR B :karl T ATTORNEY Patented May' 1, 1973 f 3,731,028

6 Sheets-Sheet 2 Sadao ANDO INVENTOR y ear! To ATTORN EY Patented May 1, 1973 3,731,028

6 Sheets-Sheet 3 Sadao ANDO INVENTOR BY .761, To"

ATTOR NEY Patented May 1, 1973 I 3,731,028

6 Sheets-Sheet 4 F/ 9. F/g/U/A/Q.

Sadao ANDO INVENTOR BY :karl 205;

ATTORNEY Patented May 1, 1973 3,731,028

6 Sheets-Sheet F,

. F/g. fO/B/ c Sadao' ANDOI INVENTOR BY Karl I0 ATTORNEY 6 Sheets-Sheet 6 Sadao ANDC INVENTOR BY :Karl To ATTORNEY- RELEASABLE LOCKING MECHANISM FOR PUSIIBUTTON SWITCII WITH PILOT-LAMP ASSEMBLY BACKGROUND OF THE INVENTION This invention relates to a pushbutton switch provided with pilot lamps.

A conventional pushbutton switch, having a plurality of pilot lamps disposed within the housing thereof, has the drawback that aspecial tool is necessary for changing the lamps which requires considerable effort; also,

the switching mechanism is liable to be inadvertently actuated when the switch is remounted after the changing of a lamp.

OBJECTS OF THE INVENTION SUMMARY OF THE INVENTION These objects are realized, in accordance with my invention, by the provision of a lamp holder which is removably seated in the housingbetween a slidable pushbutton, projecting from one end (specifically the upper end) of the housing, and a switch structure at the opposite (lower) housing end, the pushbutton being secured to a push rod which traverses the lamp holder to operate theswitch structure upon an inward (i.e. downward) depression of the pushbutton. A guide sleeve for this rod, normally coupled with it for joint rotation, is rotatably mounted on the lamp holder in an axially (i.e. vertically) fixed position and extends downwardly from the lamp holder, terminating in anchor means in the form of a pair of retaining lugs normally locking it to the housing. Rotation of the sleeve to release the retaining lugs from the housing is possible upon a removal of the pushbutton with its rod to a partly withdrawn (i.e. elevated) position in which a transverse formation on the push rod, such as a crosspin, positively engages the lamp holder for enabling axial extraction of the pushbutton, rod, sleeve and lamp holder as a unit from the housing and subsequent reinsertion of the unit after replacement of one or more burnt-out lamps. The cross-pin, which forms part of the rotarycoupling between the rod and the sleeve by being normally received in a pair of diametrically opposite longitudinal slots of the latter, has outwardly projecting tips engageable by blocking means in the form of a projection depending from the lamp holder to prevent rotation of the rod and sleeve whenever. the pushbutton is in other than the aforedescribed partly .withdrawn position, i.e. unless the pin is received in an annular recess formed in the lamp holder around the push rod; to this end the lamp holder advantageously comprises two vertically juxtaposed and rigidly interconnected plates between which this recess is formed, eg on the upper surface of the lower plate. Thus, the sleeve and the lamp holder retain their correct relative position during extraction to insure that the retaining lugs at the foot of the sleeve re-engage respective shoulders on the housing as the lamp holder returns to its seat.

According to another feature of my invention, misalignment of the lamp holder with the housingupon reinsertion is prevented by the aforementioned depending projection which confronts, upon iricorrect insertion, a boss rising within the housing. In the correct position of the lamp holder, the rising boss and the depending projection are relatively offset.

Pursuant to a further feature of this invention, the push rod is provided on one side with an elongate notch engageable by detent means in the form of an arcuate spring, lodged within the lamp holder, in the proper relative angular position of the pushbutton and the lamp holder; another notch on the opposite side of the push rod, longitudinally (i.e. vertically) offset from the first one, is engageable by the detent spring in a diametrically opposite relative angular position to prevent operative insertion of the pushbutton into the housing if the cross-pin was rotated in the wrong direction within its annular recess during reanchoring of the sleeve to the housing.

BRIEF DESCRIPTION OF THE DRAWING The above and other features of my invention will be described in detail hereinafter with reference to the accompanying drawing in which: I

FIG. 1 is a perspective exploded view of a pushbutton switch embodying a locking mechanism according to this invention;

FIG. 2 is an axial sectional view of the pushbutton assembly of the switch shown in FIG. 1;

FIG. 3 is a view similar to FIG. 2 with the pushbutton assembly partly lifted from the normal position thereof;

FIG. 4 is a view of the pushbutton lifted into the partly withdrawn position of FIG. 3 but rotated by with reference thereto;

FIGS. 2(A), 3(A) and 4(A) are fragmentary crosssectional views taken on lines IIA-IIA, IIIAIIIA and IVAIVA of FIGS. 2, 3 and 4, respectively;

FIG. 5 is a perspective exploded view of the main elements of the switch;

FIGS. 6A and 6B are a perspective view and a plan view of a plate included in the assembly;

FIG. 7 is a perspective view of a guide sleeve forming part of the assembly;

FIGS. 8(A) and 8(3) are a bottom view and a fragmentary longitudinal section of a neck depending from the pushbutton housing;

FIGS. 9, 10(A), 10(8) and II are views similar to that of FIG. 3 illustrating various steps in disassembling and reassembling the switch;

FIG. 12 is a sectional view taken on the lines XII- XII of FIG. 2; and

FIG. 13 is another sectional view illustrating the operation of the locking mechanism.

As shown in FIG. I, the pushbutton switch according to my invention comprises an actuating portion a and a switch structure b.

The actuating portion a includes a transparent pushbutton 1 of rectangular outline having indicator markings (not shown) on the upper surface thereof. A bail-shaped handle 2 is clipped onto pushbutton l in such a manner as to be detachable therefrom transversely but not by axial motion. Fixed to this handle 2 is a push rod 3 for operating the switch structure b.

An upwardly open prismatic housing 4 has its underside secured to a neck 5 depending therefrom, neck 5 terminating in a base 6 gripping the switch structure b.

A lamp holder 7, consisting of an upper plate 71 and a lower plate 72 fixed to each other (e.g. by ultrasonic welding), is removably inserted into the bottom portion of housing 4 so as to seat on lugs 41 provided within housing 4. Push rod 3 is slidably guided through a keyhole 72b, formed in the lower plate 72, and has an elongate notch 31 at one side engaged by an arcuate detent spring 74 which is fitted into an undercut 71a provided in the bottom surface of upper plate 71. A return spring 32 is inserted between the upper surface of plate 71 and the bottom surface of handle 2.

Each of four pilot lamps 8 is removably fitted from below into a respective socket 73 of lamp holder 7, the bottom of each pilot lamp abutting one of several terminal strips 42 (only two shown) provided on the bottom of housing 4.

A guide sleeve 9, into which push rod 3 is slidably inserted, is formed at its top with a flange 91 received in an annular recess 72a on the upper surface of lower plate 72, sleeve 9 being thus axially fixed with reference to lamp holder 7. A pair of longitudinal slots 92 are formed in sleeve 9, except for the lower portion thereof, and are slidably engaged by a cross-pin 33 which is fixed to push rod 3 and passes diametrically therethrough below notch 31. Sleeve 9 is slidably guided in neck 5 and is provided at its foot with a pair of lugs 93 designed to clear a keyhole 51 and engage a corresponding pair of recessed shoulders 52 on the underside of neck 5 whereby lamp holder 7 is securely anchored to housing 4.

Push rod 3 is furthermore provided with another notch 34 below notch 31 and diametrically opposite thereto, whereby the correct angular orientation of pushbutton 1 with reference to lamp holder 7 can be unequivocally determined as more fully described hereinafter.

The operation of this pushbutton switch will now be explained. In the operative condition of the switch as shown in FIG. 2, lamp holder 7 is fixedly anchored to housing 4 by means of sleeve 9, and push rod 3 is in a depressed position in which the notch 31 is engaged by the arcuate spring 74. If pushbutton 1 is now pressed, push rod 3 is lowered against the force of spring 32 to protrude downwardly from the bottom end of sleeve 9 whereby the switching mechanism b is operated. When the pushbutton 1 be released, it is returned together with rod 3 to its elevated position by the restoring force of return spring 32, this operation being generally similar to that of any conventional pushbutton switch.

If it is necessary to change any pilot lamps 8 that has been burnt out, spring 74 must first be cammed out of the downwardly beveled notch 31 by lifting the pushbutton 1 into a partly withdrawn position as shown in FIG. 3. If pushbutton 1 is then turned counterclockwise by 90, push rod 3 is rotated therewith as shown in FIG.

4, and entrains the sleeve 9 because cross-pin 33 is engaged in the slots 92, whereby the retaining lugs 93 step off the shoulders 52 to align themselves with diametrically opposite slits 51a of keyhole 51. If pushbutton 1 is further lifted in this position, push rod 3, sleeve 9 and lamp holder 7 will be lifted as a unit therewith to be disengaged from housing 4. It may be noted that cross-pin 33 now bears from below upon the bottom surface of upper plate 71 which is therefore also lifted. Accordingly, any burnt-out pilot lamp 8 may readily be pulled out from its socket 73 to be replaced by a new one.

After replacement of the defective pilot lamp 8, lamp holder 7 may be reinserted into housing 4 with all other parts reoccupying their original position; if pushbutton 1 is thereafter depressed, the relationship shown in FIG. 4 will be attained. In this condition, cross-pin 33 does not properly line up with keyhole 72b so that the downward movement of push rod 3 will be prevented. If pushbutton 1 is turned clockwise by to rotate push rod 3 before being depressed, pin 33 will pass through keyhole 72b and sleeve 9 will also be turned to re-engage its retaining lugs 93, which have passed through keyhole 51, with shoulders 52 to prevent a withdrawal of sleeve 9 from keyhole 51 whereby lamp holder 7 will be held seated on lugs 41 by means of flange 91.

If pushbutton 1 is further depressed in this position, push rod 3 will be lowered to make arcuate spring 74 enter the notch 31 so as to prevent a withdrawal of the rod unless an external force is applied thereto, thereby restoring the working condition shown in FIG. 2. As the downward pressure necessary for this re-engagement is very slight, there will be no danger of untimely actuation of the switching mechanism b.

If, when lamp holder 7 is to be inserted into housing 4 after a pilot lamp 8 has been changed, push rod 3 were erroneously rotated counterclockwise by 90 with pushbutton 1 depressed, push rod 3 could not be lowered because arcuate spring 74 would enter the notch 34, so that there is no danger that lamp holder 7 could be incorrectly positioned with reference to elements 1 3 whereby pilot lamp 8 would have a connection other than that marked on pushbutton 1.

Additional means insuring correct reassembly include a boss or projection 43 rising from the bottom of housing 4, and another projection 72d depending from the underside of lower plate 72 between the slots of keyhole 72b. Thus, if lamp holder 7 is nonnally positioned with respect to the housing, the two projections 43 and 72d are relatively offset by about the axis of rod 3 and neck 5 (see FIG. 12); if, however, lamp holder 7 were inserted into housing 4 in a position reversed with reference to its normal orientation, the two projections would buck each other so that lamp holder 7 could not be inserted any further into housing 4 so that terminal strips 42 would not reach the pilot lamps 8. Furthermore, projection 72d permits push rod 3 to rotate with respect to lamp holder 7 only when cross-pin 33 is situated within recess 72a in lower plate 72.

If projections 72d were omitted, pushbutton 1 might be rotated counterclockwise by 90 (FIG. 9) without having been sufficiently lifted to let the pin 33 pass through keyhole 72b into contact with the underside of upper plate 71 within recess 72a, whereby a subsequent upward pull as shown in FIG. (A) would bring the pin 33 up against the underside of lower plate 72 as shown in FIG. 10 (B). In this case the lamp holder 7 would be slidable with respect to push rod 3 between cross-pin 33 and handle 2. Accordingly, of lamp holder 7 were then reinserted into lamp holder 7, push rod 3 would be lowered but lamp holder 7 would not be positively entrained by pin 33; sleeve 9 would therefore tend to remain above the level at which its lugs 93 could engage the shoulders 52, resulting in unsatisfactory contact between pilot lamps 8 and terminal strips 42. However, with the tips of pin 33 sliding along the vertical edges of projection 72d as shown in FIG. 13, a rotation of pushbutton l is prevented until that pin 33 has been raised to the level of recess 72a and positively interlocks with lamp holder 7 for joint axial displacement.

I claim:

1. A pushbutton switch comprising:

a housing;

a pushbutton slidably held in said housing and projecting from one end thereof;

switch means secured to said housing at the opposite end thereof;

a lamp holder removably seated in said housing;

a guide member rotatably mounted on said lamp holder in axially fixed position, said guide member extending from said lamp holder toward said opposite end; i

a push rod guided in said member and secured to said pushbutton, said rod traversing said lamp holder for operating said switch means upon inward depression of said pushbutton;

coupling means normally interconnecting said rod and said guide member for joint rotation, said guide member being provided with anchor means normally locking same to said housing, said anchor means being releasable upon rotation of said guide member through a predetermined angle relative to said housing, said coupling means including a transverse formation on said rod positively engageable with said lamp holder in a partly withdrawn position of said pushbutton and said rod for enabling axial extraction of said pushbutton, rod, guide member and lamp holder from said housing as a unit and subsequent reinsertion of said unit into said housing; and

blocking means on said lamp holder engageable with said formation for preventing rotation of said guide member and rod in a position other than said partly withdrawn position, thereby inhibiting the release of said anchor means until said formation positively engages said lamp holder.

2. A pushbutton switch as defined in claim 1 wherein said guide member is a sleeve and said formation is a cross-pin received in a pair of diametrically opposite longitudinal slots of said sleeve upon inward displacement of said pushbutton from said partly withdrawn position.

'3. A pushbutton switch as defined in claim 2 wherein said cross-pin has tips projecting outwardly through said slots, said blocking means comprising a projection extending from said lamp holder toward said opposite end and engaging said tips upon inward displacement of said pushbutton from said artly withdrawn 3position. 4. A pushbutton switch as efined lll claim wherein said lamp holder comprises a first plate confronting said one end and a second plate confronting said opposite end, said plates being fixedly interconnected and forming between them an annular recess around said rod communicating with said slots, said cross-pin being rotatable in said recess upon removal of said pushbutton to said partly withdrawn position.

5, A pushbutton switch as defined in claim 4 wherein said housing is provided with a boss normally offset from said projection but confronting same upon angular misalignment of said lamp holder with said housing.

6. A pushbutton switch as defined in claim 5 wherein said cross-pin is rotatable in said recess in either direction, further comprising resilient detent means on said lamp holder, said rod being provided on one side with an elongate notch engageable by said detent means in a correct relative angular position of said pushbutton and said lamp holder, said rod being provided on the opposite side with another notch longitudinally offset from said elongate notch for engagement by said detent means to prevent operative insertion of said pushbutton in an incorrect position thereof relative to said housing.

7. A pushbutton switch as defined in claim 6 wherein said detent means comprises an arcuate spring received in an undercut of said first plate adjacent said recess.

cuate spring upon removal of said pushbutton to said partly withdrawn position. 

1. A pushbutton switch comprising: a housing; a pushbutton slidably held in said housing and projecting from one end thereof; switch means secured to said housing at the opposite end thereof; a lamp holder removably seated in said housing; a guide member rotatably mounted on said lamp holder in axially fixed position, said guide member extending from said lamp holder toward said opposite end; a push rod guided in said member and secured to said pushbutton, said rod traversing said lamp holder for operating said switch means upon inward depression of said pushbutton; coupling means normally interconnecting said rod and said guide member for joint rotation, said guide member being provided with anchor means normally locking same to said housing, said anchor means being releasable upon rotation of said guide member through a predetermined angle relative to said housing, said coupling means including a transverse formation on said rod positively engageable with said lamp holder in a partly withdrawn position of said pushbutton and said rod for enabling axial extraction of said pushbutton, rod, guide member and lamp holder from said housing as a unit and subsequent reinsertion of said unit into said housing; and blocking means on said lamp holder engageable with said formation for preventing rotation of said guide member and rod in a position other than said partly withdrawn position, thereby inhibiting the release of said anchor means until said formation positively engages said lamp holder.
 2. A pushbutton switch as defined in claim 1 wherein said guide member is a sleeve and said formation is a cross-pin received in a pair of diametrically opposite longitudinal slots of said sleeve upon inward displacement of said pushbutton from said partly withdrawn position.
 3. A pushbutton switch as defined in claim 2 wherein said cross-pin has tips projecting outwardly through said slots, said blocking means comprising a projection extending from said lamp holder toward said opposite end and engaging said tips upon inward displacement of said pushbutton from said partly withdrawn position.
 4. A pushbutton switch as defined in claim 3 wherein said lamp holder comprises a first plate confronting said one end and a second plate confronting said opposite end, said plates being fixedly interconnected and forming between them an annular recess around said rod communicating with said slots, said cross-pin being rotatable in said recess upon removal of said pushbutton to said partly withdrawn position.
 5. A pushbutton switch as defined in claim 4 wherein said housing is provided with a boss normally offset from said projection but confronting same upon angular misalignment of said lamp holder with said housing.
 6. A pushbutton switch as defined in claim 5 wherein said cross-pin is rotatable in said recess in either direction, further comprising resilient detent means on said lamp holder, said rod being provided on one side with an elongate notch engageable by said detent means in a correct relative angular position of said pushbutton and said lamp holder, said rod being provided on the opposite side with another notch longitudinally offset from said elongate notch for engagement by said detent means to prevent operative insertion of said pushbutton in an incorrect position thereof relative to said housing.
 7. A pushbutton switch as defined in claim 6 wherein said detent means comprises an arcuate spring received in an undercut of said first plate adjacent said recess.
 8. A pushbutton switch as defined in claim 7 wherein each of said notches has a beveled edge remote from said pushbutton to enable outward camming of said arcuate spring upOn removal of said pushbutton to said partly withdrawn position. 